The present invention relates to an irrigation chemical dispenser. More particularly, the present invention relates to a dispenser for providing water soluble or water-borne chemicals via an irrigation system to the vegetation served thereby.
A conventional dispenser for irrigation chemicals is known wherein a cup-like canister is provided which communicates with a water supply pipe of an irrigation system. A single compressed pellet of chemical material is placed into the cup-like canister. When the irrigation system operates, the water flow through the pipe is in part diverted through the canister and carries the chemical material to the vegetation by disolving or eroding the pellet of chemical material.
While this known conventional irrigation chemical dispenser is inexpensive and simple in construction and use, it also suffers from several deficiencies. For example, because the pellet of chemical material to be inserted into the cup-like canister is available in one size only, the quantity of chemical material dispensed cannot be proportioned according to the area of vegetation or number of plants served by the irrigation system. While it may be possible to attain a rough approximation of such proportioning by breaking the pellets into fractions for an irrigation system serving a small vegetation area, or providing multiple dispensers in a system serving a large vegetation area, both of these expedients are undesirable, and are inconvenient or expensive.
This known canister-type chemical dispenser is limited in its use to chemicals of solid form which can be compressed into the single pellet for inserting into the canister. While a variety of such pellets are available for grasses, evergreens, roses, etc., the conventional canister-type dispenser cannot use irrigation chemicals of liquid, paste, powder, or granular form. Also, the irrigation chemicals will be dispensed any time there is water flow, so long as there is a chemical pellet in the dispenser canister. This may not be desirable with some chemicals, such as pesticides, which it is desired to leave on the vegetation as a coating to ward off insect pests.
Another conventional irrigation chemical dispenser is known in accord with U.S. Pat. No. 4,558,715. This teaching is believed to provide a dispenser wherein a drive piston is reciprocated by flowing water under control of a valve device. The drive piston, by its reciprocation, causes reciprocation also of a metering piston. The metering piston draws a selected liquid irrigation chemical from a source thereof and injects the liquid chemical into the water flow downstream of the drive piston.
Unfortunately, the device taught by the '715 patent is both somewhat complex in its construction, and expensive. This device controls the flow of liquid irrigation chemical as a percentage of the total water flow. Such precise control of the percentage of irrigation chemical is believed not to be necessary for an irrigation system to successfully meet the needs of the vegetation served thereby. All that need be effected, in contrast, is control of the quantity of chemical material dispensed according to the vegetation area or number of plants served by the irrigation system. Optionally, control of the time during an irrigation cycle during which the irrigation chemical is dispensed is desirable. The device according to the '715 patent is limited to use of liquid irrigation chemicals. Also, this device does not provide for dispensing of the irrigation chemical at the end of an irrigation watering cycle so as to leave the chemical on the vegetation.